a single sermon after the prayer, and the same rule applied to the rain-seeking prayer. During an eclipse, likewise, he would give one sermon after finishing the prayer.
As for occasional sermons, they were delivered whenever some unforeseen circumstance arose, and the Prophet ﷺ would stand and address the people.
One example: the Prophet ﷺ once sent a man to collect zakah from those liable to pay it. When he returned to Madinah he brought with him some camels and said, “These are for you, and these were presented to me as a gift.” The Prophet ﷺ thereupon delivered a sermon and said, “What is wrong with a man whom we place in public office, and when he comes back he says, ‘This is for you and this was given to me as a gift’? Why did he not stay in his father’s and mother’s house to see whether anyone would give him gifts or not?”
The Prophet ﷺ spoke the truth: the gift was offered to that official only because of his position with the state. Had people really wanted to honour him personally, they would have given him gifts while he was sitting in his parents’ home.
From this hadith we learn how grave bribery is; it is one of the major sins that moved the Prophet ﷺ to mount the pulpit and warn the people. When bribery becomes widespread in a community, it destroys them: no one will speak the truth, judge by it, or uphold justice unless he is bribed—and we seek Allah’s refuge.